It is known that thermoplastic fluororesins have excellent oil resistance and are therefore useful as a material in fuel hoses for automobiles and aircraft. However fluororesins are poor in flexion properties in that they are liable to fatigue, leading to rupture. For this reason fluororesins are not used alone to make fuel hoses. Rather, an epichlorohydrin rubber or ethylene-acrylate rubber is used to provide an outer layer for the hose, with the fluororesin as an inner layer.
In recent years there has been increasing demand for fuel hoses with better heat resistance. Ethylene acrylate rubbers have generally good heat resistance. But, their oil/fuel resistance is poor leading to danger if the inner fluororesin layer ruptures. Epichlorohydrin rubbers are better in this respect, but their heat resistance is poor.